Binary Pd-Co alloy nanoparticles decorated on graphene-Vulcan carbon hybrid support: An efficient and cost-effective electrocatalyst for hydrogen evolution reaction in electrochemical methanol reformation

Abstract

• Synthesis of nanostructured graphene-vulcan carbon supported Pd-Co nanocomposite. • Enhanced HER with lower onset potential, less Tafel slope and current density. • Evaluation of Pd 3 -Co 1 /G-C as cathode catalyst for hydrogen production. • Pd 3 -Co 1 /G-C can be used as an alternative electrocatalyst for HER in ECMR cell. In the future of renewable energy, the hydrogen evolution reaction (HER) is an important component of various energy storage and conversation systems. Similar to other evolution reactions, HER needs a considerable overpotential, and thus, it is vital to find appropriate electrocatalysts to maximize the process efficiency. The development of low-cost cathodic electrocatalysts for HER in electrochemical methanol reformation (ECMR) cell could be an alternative pathway for sustainable energy needs. The present work reports an eco-friendly and simple route to synthesize Pd 3 -Co 1 /Graphene (G)-Vulcan carbon (C) (Pd 3 -Co 1 /G-C) a novel hybrid electrocatalyst. Through chemical reduction, Pd 3 -Co 1 nanoparticles were uniformly distributed over a prepared G-C hybrid carbon support to obtain Pd 3 -Co 1 /G-C. The synthesized electrocatalyst was physically and morphologically characterized using several techniques such as XRD, FT-IR, FE-SEM, EDX, TEM, SAED, ICP-OES and XPS. The electrocatalytic activity of the developed electrocatalyst for HER was evaluated by electrochemical characterization techniques such as CV, LSV and EIS. The prepared electrocatalyst exhibited high electrochemical surface area (154 m 2 g −1 ), small Tafel slope value (35 mV dec -1 ), low charge transfer resistance (9 Ω) and long-term stability as compared to Pd 3 -Co 1 /G, Pd 3 -Co 1 /C control and commercial Pt/C catalysts. The improved electrocatalytic activity was attributed to the G-C hybrid carbon support which provided better mass transport and utilization of the electrocatalyst layer. This could be inferred from the FE-SEM analysis, where Pd 3 -Co 1 /G-C containing G-C hybrid support showed a better catalytic layer due to the presence of more active Pd 3 -Co 1 nanoparticles as compared to individual graphene and carbon support. These results are also supported by LSV measurements. Further, the performance of Pd 3 -Co 1 /G-C was evaluated in a single ECMR cell using commercial Pt-Ru/C and synthesized Pd 3 -Co 1 /G-C as anode and cathode electrocatalysts, respectively. Cell studies confirmed the practical utility of the synthesized Pd 3 -Co 1 /G-C as an efficient cathode electrocatalyst for HER in the ECMR process.